Help selecting o/d gear ratio

[Buford19]

Going to order a 5 speed tremec tranmission tomorrow, I have a option of a .82 or .64 overdrive fifth gear. Which would you choose. Going to be running 410 rear end with 28 inch tall tires. The engine will be a 6.4 gen 3 hemi in a 67 barracuda.

 

[Steven190]

I run the TKO .68 with 3:91's 5 speed.
Got the kit from Hurst, a good experience with them

 

[mderoy340]

Calculate your highway cruise rpm in overdrive and make sure your cam will perform in the lower rpm band.

 

[teringer]

.64 I used a .68 with a 2.94 ratio and its flat at highway speeds unless I going 80 because of a cam that's too big, but with a 4.10 it was perfect

 

[NudeHemidude]

Tremec has an iPhone app that calculates all the rpm at various diff ratios and tire heights with their 5 and 6 speed transmissions. I think I found out about it from their website. Tremec.com